The Royal Library is Denmark's Book Museum and as such it holds invaluable book historical collections, Danish as well as foreign. The Library comprises both the collections of the 'old' Royal Library and of the University Library.
As a rule rare books can only be studied at the Centre for Manuscripts and Rare Books, in some cases, though, at Reading Room West.
Read more below. From here you are directed to the Department of Manuscripts and Rare Books.